Arthritis trends favorably; psoriasis improves or remains stable

Action Points

In women with psoriatic arthritis (PsA), pregnancy was associated with a favorable arthritis course in 58.5% of the pregnancies, while the skin disease showed a favorable course in 88.2% of the pregnancies, in a small Canadian study.

Note that in the first postpartum year, arthritis had a favorable course in 52.5% of pregnancies and a worsening course in 40%.

Psoriasis improved or remained in a stable, low-activity state in 88.2% of pregnancies of women with PsA. Arthritis improved or was at a stable, low-activity level in 58.5% of PsA pregnancies. Compared with a control group, the pregnant patients had a significantly better course in skin disease (OR 6.8; P=0.004), but not in joint disease.

"The outcome of pregnancy among patients with PsA is excellent," wrote Dafna Gladman, MD, of the University of Toronto Psoriatic Arthritis Program, and colleagues. "Arthritis activity trends toward a favorable course, while skin disease shows a favorable course in pregnancy."

The researchers drew their sample from their arthritis clinic, which has been following patients prospectively since 1978. The team evaluated 29 women with PsA who had a total of 42 pregnancies, matching them with 67 control patients of similar ages who also had PsA, but who were not pregnant. All patients had visited the clinic between 1990 and 2015.

The average age of women in the sample when pregnancy began was 33.8. Most of the women had one pregnancy, seven had two pregnancies, and three had three. The majority of pregnancies, 86%, occurred after 2000. Of the 42 pregnancies, 40 (95%) resulted in a normal live birth, and two ended in miscarriage. In total, 41 women began follow-up before pregnancy (one woman started follow-up during her first trimester).

Two-thirds of the women used medications for PsA during pregnancy -- notably non-steroidal anti-inflammatory drugs (NSAIDs) at 40.5%, disease-modifying anti-rheumatic drugs (DMARDs) at 35%, and biologic agents at 26%. Over the years of the study, more patients used drugs during pregnancy, including a growing use of biologics.

The researchers compared the active (tender or swollen) joint count and psoriatic area severity index (PASI) during pregnancy with those in the last pre-pregnancy visit. The course of joint and skin disease activity was categorized into the following five states: improvement, worsening, stable low, stable high, or mixed. A decrease of at least two active joints was defined as improvement, and an increase of at least two active joints was defined as worsening. Likewise, the researchers identified a reduction of at least two in the PASI as improvement and an increase of two, as worsening.

The researchers found that during pregnancy:

Arthritis had a favorable course in 24 of 41 pregnancies (58.5%): joint activity improved in 11 (26.8%), and stayed stable at a low level in 13 (31.7%)

Arthritis had an unfavorable course during 13 of 41 pregnancies (31.7%), as evidenced by worsening during eight pregnancies (19.5%) or stable high disease activity during five (12.2%)

Psoriasis had a favorable course in 30 of 34 pregnancies (88.2%): skin activity improved in 11 (32.3%) cases, and disease activity was low in 19 (55.9%)

The results also showed that during the 1-year postpartum period:

Arthritis had a favorable course in the first year after giving birth in 21 of 40 pregnancies (52.5%): eight (20%) had improved joint activity, and 13 (32.5%) had stable low disease activity

Arthritis had an unfavorable postpartum course in 16 of 40 pregnancies (40%; all worsening)

Postpartum psoriasis had a favorable postpartum course in 16 of 35 pregnancies (45.7%), but an unfavorable course in 15 (42.9%) pregnancies

Comparing these women with the control group, the researchers observed that pregnancy had a significant beneficial effect on psoriasis. The likelihood of improved skin activity during pregnancy rose significantly (OR 6.8; P=0.004), compared with a matched period among the control group. Other odds ratios -- comparing postpartum joint or skin activity, or pregnancy-period joint activity between the two groups -- did not reach statistical significance.

The results also showed that patients with low PsA activity before conceiving a child had more favorable outcomes during pregnancy, compared with patients with high disease activity. Gladman et al suggested that controlling disease activity before conception might lead to better PsA outcomes during pregnancy.

The authors also speculated that higher levels of estrogen might explain skin improvement during pregnancy. In addition, most women with more than one pregnancy had a different joint disease course during each pregnancy and postpartum period, pointing to the need, the team said, for specific evaluation and treatment during each pregnancy.

The investigators noted that although this was the largest pregnancy study in PsA to date, the sample size was still relatively small. The low number of cases, therefore, led the researchers to expand the time frame of the study to 25 years, which might have influenced the consistency of results, since biologics were introduced and PsA treatment became more aggressive during the last 10 years of the study.

The University of Toronto Psoriatic Arthritis Program is supported by a grant from the Krembil Foundation.

One of the study authors, Ari Polachek, MD, is supported by an educational grant from Janssen Canada. No other disclosures were noted.

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